Fire Red and Leaf Green
The starting Pokémon in Fire Red and Leaf Green are the same as they were in the original games; Charmander, Squirtle, and Bulbasaur.
Bulbasaur is the only dual-type starting Pokémon, having both a Grass and Poison type. Its ability is Overgrow, and some of its common attacks are Vine Whip, Razor Leaf, and Solarbeam. Bulbasaur's evolutions are Ivysaur and Venusaur.
Charmander is the Fire type starter. It has the ability Blaze, and can learn Ember, Metal Claw, and Flamethrower. Its evolutions are Charmeleon and Charizard, and upon reaching its final evolution, it gains a Flying type.
Squirtle is the Water starter. Common attacks are Bubble, Water Gun, and Bite. This Pokémon has the ability Torrent, and its evolutions are Wartortle and Blastoise.
Squirtle and Bulbasaur are effective against the first gym leader, where Charmander does poorly. Bulbasaur is the best against the second gym leader, Squirtle won't do much damage, and Charmander will take a beating. Bulbasaur and Charmander will be strong against the third gym leader, and Squirtle will probably be creamed. Against the fourth gym leader, Charmander is best, Squirtle is worst, and Bulbasaur is kind of neutral.
Overall, whichever starter you choose, it's bound to be a good choice.